Research Provides Insights into Connections Between Sleep and Diabetes

Diabetes and sleep problems often go hand in hand. It has been known for some time that diabetes-associated factors such as neuropathy and nighttime hypoglycemia can contribute to sleep problems in patients. Research is now providing growing evidence that insufficient sleep can also contribute to diabetes risk. The most recent studies reveal some of the potential mechanisms behind this link.

“Sleep can affect diabetes, and diabetes can affect sleep,” said Elizabeth Bashoff, MD, of the Joslin Diabetes Center in Boston. “For everyone, but especially for patients with chronic conditions such as diabetes, it’s important to take care of your health overall to improve sleep, and to take steps to get a good night’s sleep to restore the body.”

How diabetes affects sleep

Fluctuations in blood glucose can be particularly disruptive to sleep for many individuals with diabetes. “It’s not uncommon for people to experience hypoglycemia in the middle of the night, which can cause headaches, sweating, and nightmares,” Bashoff said. “Blood glucose that is too high can also be a problem because it may cause people to wake up repeatedly to use the bathroom.”

Sleep apnea is also a major cause of sleep problems, and it is more common in individuals with diabetes than in the general population. Sleep apnea is linked to obesity, and weight loss is by far the most effective treatment for individuals with sleep apnea who have high BMIs.

Leg pain due to neuropathy can also keep diabetics up at night. Controlling blood sugar levels can help. Also, there are many medications to treat the condition, some of which also have a beneficial sedative effect at bedtime.

How sleep affects diabetes

While diabetes and its associated complications can have clear impacts on sleep quality, sleep quality may also impact diabetes and diabetes risk.

The first clue to this connection came from a 1999 study published in The Lancet. The study found that restricting healthy young people’s sleep to just four hours for six nights in a row produced striking changes in glucose tolerance and endocrine function (Spiegel K et al. Lancet 1999; 354:1435–1439).

Since then, studies have generated additional evidence that disrupted sleep affects insulin resistance, and that individuals with diabetes who keep regular sleep schedules seem to maintain better blood sugar control, perhaps in part due to circadian rhythms connected to glucose metabolism. Also, research suggests that people who get less sleep tend to be heavier than those who sleep well, which puts them at increased risk for developing type 2 diabetes.

Research is starting to tease out the mechanisms by which sleep affects diabetes risk. A new Journal of the American Medical Association study found that individuals who secrete low levels of melatonin at night have about twice the risk of developing type 2 diabetes as individuals who secrete high levels of the hormone (McMullan CJ, et al. JAMA 2013; 309:1388–1389). The study included 370 women who developed diabetes and 370 controls. Melatonin secretion was measured at the start of the study, when none of the participants had diabetes. Women in the highest category of melatonin secretion had an estimated diabetes incidence rate of 4.27 cases/1000 person-years compared with 9.27 cases/1000 person-years in the lowest category.

“This is the first time that an independent association has been established between nocturnal melatonin secretion and type 2 diabetes risk,” said first author Ciaran McMullan, MD, a nephrologist at Brigham and Women’s Hospital in Boston. “Hopefully this study will prompt future research to examine what influences a person’s melatonin secretion and what is melatonin’s role in altering a person’s glucose metabolism and risk of diabetes.”

New evidence presented at SLEEP 2012, the 26th annual meeting of the Associated Professional Sleep Societies, links sleep apnea with carbohydrate craving. Researchers screened 55 individuals (more than half of whom had diabetes) for sleep apnea and carbohydrate cravings. They found that among the diabetic patients, the prevalence of sleep apnea was 82 percent, and they had almost twice the risk of carbohydrate craving than nondiabetics. In addition, patients with sleep apnea were almost twice as likely to have high carbohydrate craving than were patients without sleep apnea.

“Previous studies have shown that sleep deprivation may lead to changes in hormones that regulate appetite and hunger. These hormonal changes can lead to significant craving for high-calorie carbohydrates,” said study co-investigator Mahmood Siddique, DO, of the department of medicine at the Robert Wood Johnson Medical School in New Brunswick, NJ. “This study supports previous findings by validating this in a community sample of diabetics.”

Getting a good night’s sleep

While some aspects of sleep may be out of one’s control, experts agree that certain measures can help improve sleep for most people, leading to considerably better health.

“Maintaining a regular schedule, getting exercise, avoiding alcohol at night—and for people with diabetes, testing blood sugar at bedtime—can lead to a better night’s sleep,” said Bashoff. “I often see patients who are so busy that they don’t think of these simple steps.”

Individuals who sleep poorly are susceptible to depression and other mood disorders, changes in eating, decreases in physical activity—and as indicated by the latest evidence, perhaps an increased risk of developing diabetes.